The present invention relates generally to the field of diplexers and, more specifically, to the field of diplexers constructed in stripline and microstrip. Various filter arrangements have been used in wave guide and stripline. Most of these arrangements are unsuitable for microstrip at millimeter wave frequencies where no tuning procedures can be used and filters requiring grounded sections generally can not be used.
Comb-line filter arrangements have been used in the past for broad band diplexers. These filters, however, require ground connections which degrade performance at millimeter wave frequencies.